Notice: On March 31, it was **announced** that Statalist is moving from an email list to a **forum**. The old list will shut down on April 23, and its replacement, **statalist.org** is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: XTLOGIT: Predicted Diminishing Returns |

Date |
Tue, 17 May 2011 19:06:18 +0200 |

On Tue, May 17, 2011 at 6:37 PM, Dennis Kramer wrote: > I am using a --xtlogit-- model to predict the probability of passing > an assessment based on student and teacher absences. I am using the > following commands: > > xtset STUDENT_COURSE_ID YEAR > xi: xtlogit Test_Score STD_Absent Tch_Absent STD_TCH_Absence > i.Course_Grade male i.race frl lep migrant gifted CLASS_MEAN i.year, > or > > However, I want to get the predicted probabilities of passing for each > individual absence value. Meaning, I want to look at the probability > of passing the test with missing one, two, three, etc days. > Theoretically there must be some diminishing impact on passing as > going from 1 to 2days absent might be more influential then going from > 15 to 16 days. I can see two solutions: 1) Treat STD_Absent and Tch_Absent as categorical variables, that is include them as i.STD_Absent i.Tch_Absent. This is a literary interpretation of your question. You will get lots of coefficients, and you may have to combine some of the rarer "categories", e.g. 1, 2, 3, 4-5, 5-10, etc. in order to get meaningful (or even converging) estimates. 2) Enter STD_Absent and Tch_Absent as non-linear functions. Entering the logarithm of STD_Absent and Tch_Absent would make sense. I actually like linear splines for this thing, as they are easy to interpret (*), allow for decreasing effects but do not force it, and they are nested in a model with simple linear effects. See -help mkspline- Hope this helps, Maarten (*), see for example: http://www.stata.com/statalist/archive/2010-08/msg01430.html -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: XTLOGIT: Predicted Diminishing Returns***From:*Dennis Kramer <dkramerii@gmail.com>

- Prev by Date:
**st: RE: creating variable summarizing for each individual properties of other members of a group at t-1** - Next by Date:
**st: svyset with DHS subsample** - Previous by thread:
**st: XTLOGIT: Predicted Diminishing Returns** - Next by thread:
**st: dhs data in stata number of obs and population size** - Index(es):